Titanium, 422 oxyhydroxides

Titanium oxyhydroxide Electrochemically induced sol-gel process 450, 24 Diameter 40 - Anatase Single- crystaUine nanowires [147]... 

Figure 12.1 Laser light attenuation during precipitation of titanium oxyhydroxide particles in the absence (a) and presence (b) of gravity. The Ti(iPro)< concentration was 2 mmol, and the stirring rate 500 r.p.m (Heimann, 1990).

Figure 12.2 Titanium oxyhydroxide particles precipitated through hydrolysis and polycondensation of titanium tetraisopropoxide at (a) g 0 and (b) g = 1. Stirring rate a = 250 r.p.m., concentration c = 4mmol (Heimann, 1990).

Chem. Soc. Faraday Trans. I. 71 1623-1630 Rustad, J.R. Felmy A.R. Hay, B.P. (1996) Molecular statics calculations for iron oxide and oxyhydroxide minerals Toward a flexible model of the reactive mineral-water interface. Geochim. Cosmochim. Acta 60 1553—1562 Ryan, J.N. Gschwend, P.M. (1991) Extraction of iron oxides from sediments using reductive dissolution by titanium(III). Clays Clay Min. 39 509-518... 

Other metals, such as copper, nickel, or silver, have been used as electrode materials in connection with specific applications, such as the detection of amino acids or carbohydrates in alkaline media (copper and nickel) and cyanide or sulfur compounds (silver). Unlike platinum or gold electrodes, these electrodes offer a stable response for carbohydrates at constant potentials, through the formation of high-valence oxyhydroxide species formed in situ on the surface and believed to act as redox mediators (40,41). Bismuth film electrodes (preplated or in situ plated ones) have been shown to be an attractive alternative to mercury films used for stripping voltammetry of trace metals (42,43). Alloy electrodes (e.g., platinum-ruthenium, nickel-titanium) are also being used for addressing adsorption or corrosion effects of one of their components. The bifunctional catalytic mechanism of alloy electrodes (such as Pt-Ru or Pt-Sn ones) has been particularly useful for fuel cell applications (44). 

Titanium (Ti) exists in the + 3 oxidation state as the neutral oxyhydroxide, TiO(OH)2, in sea water. Dissolved titanium ranges from 4 to 300 pmol with the lowest values in the surface waters of the North Pacific and the highest values in the deep waters. Vertical profiles of dissolved titanium in the Pacific show a minimum in the surface waters, with gradually increasing concentrations with depth to a maximum at the bottom. Dissolved titanium concentrations in surface waters range from 4 to 8 pmol 1 in the North Pacific, from 50 to 100 pmol... 

Very recently, many studies have been conducted to identify new reinforcing systems. These systems are similar to silica compounds and characterized by the use of a coupling agent to chemically bond elastomer chains to filler surface. Many reinforcing systems have been patented alumina oxyhydroxide and oxide [18,19], titanium oxides [20], and silicon nitride/carbide [21]. 

Ferro-, Antiferro-, and Ferrimagnetic Minerals The most important and abundant groups are iron and iron-titanium (Fe-Ti) oxides. Iron oxyhydroxides and iron sulphides are significant, but not abundant (Bieil and Petersen, 1982). 

Solubility data are available for the trivalent oxide phase of titanium(III), Ti203(s). It is quite probable that the hydroxide phase and possibly the mixed oxyhydroxide phase also exist, but no solubility data are available for these phases. 

The derivatographic study [81] of reaction in the temperature range 25-800°C demonstrated that the main weight loss of the reaction system, which is equal to approximately 10% (Figure 21), is observed in the temperature range 600-780°C and accompanied by endothermic effects at temperatures of 600, 660, and 780°C. The endothermic effects at temperatures of 300 and 500°C with a small weight loss correspond to the decomposition of neodymium hydroxide with the formation of neodymium oxyhydroxide and neodymium oxide, which is explained by the activity of neodymium oxide in the reaction with water. The thermal analysis of the binary mixture of sodium carbonate and titanium oxide reproduces the endothermic effects at 600 and 660°C. 

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